Corrosion Under Insulation (CUI)

Corrosion Under Insulation (CUI) is one of the most well-known phenomena in the process industries, and yet it still makes up an inordinately large percentage of global maintenance expenditures. CUI is a subject that is well-researched and understood; extensive studies have been commissioned to determine the causes, effects, prevention, and mitigation of CUI.

In the simplest terms, CUI is any type of corrosion that occurs due to moisture present on the external surface of insulated equipment. The damage/attack can be caused by one of the multiple factors, and can occur in equipment operating at ambient, low, and heated services, depending upon conditions. Moreover, CUI can occur in equipment that is in service, out of service, or in cyclic service.

The corrosion itself is most commonly galvanic, chloride, acidic, or alkaline corrosion. If undetected, the results of CUI can lead to leaks and the shutdown of a process unit or an entire facility.

Codes, Standards, and Best Practices

API 510, Pressure Vessel Inspector Program is an inspection code that covers the in-service inspection, repair, alteration, and rerating activities for pressure vessels and the pressure relieving devices protecting these vessels. It applies to most refining and chemical process vessels that have been placed into service. CUI inspection is covered in section 5.5.6 of the standard (Tenth Edition released April, 2014).

Are you giving CUF the attention it deserves? Learn the vital role fireproofing plays in maintaining the integrity and reliability of what it protects as well as what's needed for managing potential CUF issues.

Myths, challenges, and good practices related to process piping integrity management activities that help inspection and maintenance managers make the right decisions to develop cost-effective piping inspection plans without compromising the asset’s reliability or performance.

Beyond the financial hits, undetected degradation from corrosion can also lead to critical safety risks. To effectively manage mechanical integrity, organizations need reliable methods of identifying the current states of corrosion occurring within their assets.

Did you ever wonder where you fit into the entire hierarchy of a fixed equipment asset integrity management (FE-AIM) program? Or who is responsible and accountable for what aspects of FE-AIM at your site? All the way from top management down to those doing the work at the field level? That’s what I will try to address in this article.

Corrosion Under Insulation (CUI) is an insidious damage mechanism that, despite being incredibly well-known and understood, still makes up an inordinately large percentage of global maintenance expenditures. CUI has been extensively researched and studied and because of that, there exist several good resources on it, and we at Inspectioneering are dedicated to bringing those resources to you.

Offshore platforms are exposed to some of the roughest conditions on earth and require regular attention to ensure they are structurally sound and safe for continued operation. With so many components and major joints at elevated locations, it is clear why a well-trained rope access technician can be an invaluable resource for offshore operators.

I've crunched some numbers and have come up with the three most popular damage mechanisms, based on the activity of our readers, that Inspectioneering publishes information on. I've limited the list to these three mechanisms for the sake of brevity, but keep in mind that there are nearly a hundred different damage mechanisms that affect fixed equipment mechanical integrity in the oil & gas and chemical industries.

As any refining or petrochemical plant manager knows, corrosion can occur on insulated piping at any facility, and is particularly difficult to prevent, track, and mitigate. Corrosion under insulation (CUI) has been a major challenge for the petrochemical and refining industries since the first pipelines were insulated with wrappings.

In many ways, fertilizer plants are no different than most process industry plants including refineries and petrochemical facilities. Information in documents like API 510, 570, 653 and RPs 580, 581, 571, 577, 579, etc. is essential.

Over recent years large strides have been made in application, development, and utilization of Digital Detector Arrays (DDAs) in field radiography environments (an application previously limited to film and computed radiography [CR] techniques).

The Vanta handheld XRF is Olympus’ first full spectrum PMI analyzer that is IP65 rated and drop tested. The analyzer provides accurate, repeatable material chemistry and alloy grade matching in as little as 1–2 seconds. Operation is simple with an intuitive touch screen and swipe interface. Optional Wi-Fi, with the Olympus Scientific Cloud, provides seamless connectivity for efficient data and fleet management.

This week’s post takes up right where last week’s post left off in our discussion on Corrosion Management and Control (CM&C) Management Systems. As I have said previously, this information is based off a series of articles I did on PEI&R MS, which you can reference here. Here are the next four...

CUI (Corrosion Under Insulation) has always been a challenge for plant operators, quality assurance/reliability engineers and equipment owners. It is hard to identify the problem until it has become an emergency situation, often leading to unit shut downs or even the whole facility shut down for emergency repairs.

Nearly ten years ago the magnetostrictive sensor (MsS) technology was reported in this journal (July/August 1996 Issue, Volume 2 Issue 4) as a method to detect corrosion in insulated piping. At that time, the MsS Technology consisted primarily of the longitudinal guided wave mode introduced into the pipe with a coil wrapped around the steel pipe with a coil wrapped around the steel pipe and a number of large magnets setting up an axially oriented magnetic baising field in the area of the coil. The longitudinal mode worked well for dry, unfilled pipe. However, in liquid filled pipes, the longitudinal mode didn't work well because it interacts with the liquid, producing extraneous signals that, in turn, cause difficulty in analyzing data.

Exactly two years ago, an interview with John Nyholt appeared in the “IJ”. New ground will be covered in this interchange. We at the IJ thought it might be valuable to spend some time chatting about his background, challenges he has faced recently and what he feels are some of the biggest challenges ahead for the Inspectioneering® community.

Chloride cracking of austenitic stainless steels (300 series SS) is an off-shoot of CUI, and there’s nothing really magical about it. If you have insulated solid stainless steel equipment operating in the CUI temperature range you are likely to eventually experience External Chloride Stress Corrosion Cracking (ECSCC).

CUI may be the most well known and widespread corrosion phenomena in our industry. It’s also one of the most difficult to prevent because by and large no matter what precautions we take, water eventually gets into the insulation and begins to do it’s dirty work, sometimes sight unseen until process leakage occurs. And it’s not isolated to just insulation. Corrosion under fire-proofing (CUF) is also prevalent in our industry and requires the same type of inspection planning, design prevention, and mitigation that is required for CUI.

Determination of the mechanical integrity of pipe and equipment in US process industries has evolved from day to day business to federal mandate (OSHA 1901.119) to a part of industry best practice. Insulated pipe and equipment pose specific challenges for the examination effort. This article is an attempt to review the regulations that are driving these efforts and the innovations designed to address these challenges. Understanding both will enhance the value added services offered by the insulation industry.

This article continues to outline the 101 essential elements that need to be in place, and functioning well, to effectively and efficiently, preserve and protect the reliability and integrity of pressure equipment (vessels, exchangers, furnaces, boilers, piping, tanks, relief systems) in the refining and petrochemical industry.

Corrosion under insulation (CUI) is a real threat to the onstream reliability of many of today's plants. This type of corrosion can cause failures in areas that are not normally of a primary concern to an inspection program. The failures are often the result of localized corrosion and not general wasting over a large area. These failures can be catastrophic in nature, or at least, have an adverse economic effect in terms of downtime and repairs.

Engineers and scientists at Southwest Research Institute (SwRI) in San Antonio, Texas, may have found a cost-effective and practical method of detecting ID and OD corrosion of insulated piping systems.

In May 1995, Omega International Technology, Inc., began testing a new system to measure pipe wall thicknesses using digital radiography (RT) scanning. This new system has the potential for being faster, less labor intensive, and shown improved accuracy over traditional ultrasound testing, and at a lower cost. Perhaps best of all, scanning can be performed while the pipe is in service, insulation in place.

Corrosion is one of those "equal opportunity" hazards that affects all industries indiscriminately, to the tune of billions of dollars annually in repair and replacement costs. Some types of corrosion are readily apparent, such as rusting of unprotected plain carbon steel tanks and piping.

This publication outlines 101 Essential Elements that need to be in place and functioning well in order to effectively and efficiently preserve and protect the reliability and integrity of pressure equipment (i.e. vessels, exchangers, furnaces, boilers, piping, tanks, and relief systems) in the refining and petrochemical industry.

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